A new finger joint prosthesis is to be designed and tested. It will utilize a titanium hinge. The hinge area is to be encapsulated in an elastomeric jacket whose exterior will have an integrally textured surface designed to promote soft tissue ingrowth and attachment. This potentially minimizes reactive scar tissue formation around the flexing part of the implant, resulting in improved joint function. The tapered proximal and distal terminations of the prosthesis will utilize a porous, sintered metal surface to permit implantation of the device without the use of adhesive cements when inserted into the medullary cavity of the bone. Bone growth into the porous metal surface is the means of fixation. A totally porous surface device offers the advantage also of reduced potential for bacterial colonization of the implant site, a generally disastrous complication with orthopedic prostheses. A series of 12 prototypes will be flex tested in vitro for 10 million cycles to characterize device reliability. Following that, 6 prostheses will then be implanted in the knee joint of adult New Zealand white rabbits, with silicone rubber joint spacer prostheses contralaterally implanted as controls. After 8 weeks, the animals will be sacrificed, and the prostheses and surrounding tissues removed for histopathologic evaluation using light and scanning electron microscopy. A quantitative comparison of device fixation and tissue capsule structure will then be possible.